Design and synthesis of 4′‐((5‐benzylidene‐2,4‐dioxothiazolidin‐3‐yl)methyl)biphenyl‐2‐carbonitrile analogs as bacterial peptide deformylase inhibitors

Herein, we report the synthesis and screening of 4′‐((5‐benzylidene‐2,4‐dioxothiazolidin‐3‐yl)methyl)biphenyl‐2‐carbonitrile analogs 11(a–j) as bacterial peptide deformylase (PDF) enzyme inhibitors. The compounds 11b (IC₅₀ value = 139.28 μm ), 11g (IC₅₀ value = 136.18 μm ), and 11h (IC₅₀ value = 131.65 μm ) had shown good PDF inhibition activity. The compounds 11b (MIC range = 103.36–167.26 μg/mL), 11g (MIC range = 93.75–145.67 μg/mL), and 11h (MIC range = 63.61–126.63 μg/mL) had also shown potent antibacterial activity when compared with standard ampicillin (MIC range = 100.00–250.00 μg/mL). Thus, the active derivatives were not only PDF inhibitors but also efficient antibacterial agents. To gain more insight on the binding mode of the compounds with PDF enzyme, the synthesized compounds 11(a–j) were docked against PDF enzyme of Escherichia coli and compounds exhibited good binding properties. The results suggest that this class of compounds has potential for development and use in future as antibacterial drugs.     

Design,Synthesis, and Biological Evaluation of 1‐(thiophen‐2‐yl)‐9H‐pyrido[3,4‐b]indole Derivatives as Anti‐HIV‐1 Agents

A novel series of 1‐(thiophen‐2‐yl)‐9H‐pyrido [3,4‐b]indole derivatives were synthesized using DL‐tryptophan as starting material. All the compounds were characterized by spectral analysis such as ¹H NMR, Mass, IR, elemental analysis and evaluated for inhibitory potency against HIV‐1 replication. Among the reported analogues, compound 7g exhibited significant anti‐HIV activity with EC₅₀ 0.53 μm and selectivity index 483; compounds 7e , 7i , and 7o displayed moderate activity with EC₅₀ 3.8, 3.8, and 2.8 μm and selectivity index >105, >105, and 3.85, respectively. Interestingly, compound 7g inhibited p24 antigen expression in acute HIV‐1_IIIB infected cell line C8166 with EC₅₀ 1.1 μm . In this study, we also reported the Lipinski rule of 5 parameters, predicted toxicity profile, drug‐likeness, and drug score of the synthesized analogues.     

Synthesis and Biological Evaluation of a Series of 2‐((1‐substituted‐1H‐1,2,3‐triazol‐4‐yl)methylthio)‐6‐(naphthalen‐1‐ylmethyl)pyrimidin‐4(3H)‐one As Potential HIV‐1 Inhibitors

A series of novel S‐DABO derivatives with the substituted 1,2,3‐triazole moiety on the C‐2 side chain were synthesized using the simple and efficient CuAAC reaction, and biologically evaluated as inhibitors of HIV‐1. Among them, the most active HIV‐1 inhibitor was compound 4‐((4‐((4‐(2,6‐dichlorobenzyl)‐5‐methyl‐6‐oxo‐1,6‐dihydropyrimidin‐2‐ylthio)methyl)‐1H‐1,2,3‐triazol‐1‐yl)methyl)benzenesulfonamide ( B5b7) , which exhibited similar HIV‐1 inhibitory potency (EC₅₀ = 3.22 μm ) compared with 3TC (EC₅₀ = 2.24 μm ). None of these compounds demonstrated inhibition against HIV‐2 replication. The preliminary structure–activity relationship (SAR) of these new derivatives was discussed briefly.     

A Facile One‐Pot Synthesis of 2‐Arylamino‐5‐Aryloxylalkyl‐1,3,4‐Oxadiazoles and Their Urease Inhibition Studies

A one‐pot method for the synthesis of structural type urease inhibitors, 2‐amino‐1,3,4‐oxadiazoles, was developed. The structures of the compounds were established using spectroanalytical techniques and unambiguously confirmed by single‐crystal X‐ray analysis of compound 3o . The synthesized compounds were tested against jack beans urease, and most of the compounds ( 3c , 3g , 3j , 3k , 3n , 3r – 3v ) were found more active than the standard. The most potent compound ( 3u ) had an IC₅₀ value of 6.03 ± 0.02 μm as compared to the IC₅₀ value of the standard (thiourea; 22.0 ± 1.2 μm ). The prominent urease inhibition activity of these compounds may serve as an important finding in the development of less toxic and more potent antiulcer drugs. The compounds were also investigated against four bacterial strains, and some of the compounds ( 3g and 3r ) were found more potent than the standard drug (ciprofloxacin) against all the tested strains. The MIC value for compound 3g was 0.156 μmol/mL against the tested bacterial strains.     

Novel 3‐Substituted Ocotillol‐Type Triterpenoid Derivatives as Antibacterial Candidates

Plant‐derived triterpenoid saponins are involved in the plant defense system by targeting bacterial membranes. A series of ocotillol‐type triterpenoid derivatives were synthesized starting from PPD, one of the main components of Panax ginseng and their antibacterial activity against several representative bacteria were evaluated. Compounds 5 and 11 exhibited excellent antibacterial activity with MIC values of 1 μg/mL against Staphylococcus aureus and 8 μg/mL and 4 μg/mL against Bacillus subtilis, respectively. Furthermore, when compounds 5 and 11 were combined with two commercial antibiotics kanamycin and chloramphenicol, they showed strong synergistic activity at sub‐MIC levels against S. aureus USA300 and B. subtilis 168. Moreover, chloramphenicol turned from a bacteriostatic to a bactericidal agent when combined with compound 11 against B. subtilis 168.     

Design,Synthesis, Antibacterial Evaluation and Docking Study of Novel 2‐Hydroxy‐3‐(nitroimidazolyl)‐propyl‐derived Quinolone

A novel series of 2‐hydroxy‐3‐(nitroimidazolyl)‐propyl‐derived quinolones 6a – o were synthesized and evaluated for their in vitro antibacterial activity. Most of the target compounds exhibited potent activity against Gram‐positive strains. Among them, moxifloxacin analog 6n displayed the most potent activity against Gram‐positive strains including S. epidermidis (MIC = 0.06 μg/mL), MSSE (MIC = 0.125 μg/mL), MRSE (MIC = 0.03 μg/mL), S. aureus (MIC = 0.125 μg/mL), MSSA (MIC = 0.125 μg/mL), (MIC = 2 μg/mL). Its activity against MRSA was eightfold more potent than reference drug gatifloxacin. Finally, docking study of the target compound 6n revealed that the binding model of quinolone nucleus was similar to that of gatifloxacin and the 2‐hydroxy‐3‐(nitroimidazolyl)‐propyl group formed two additional hydrogen bonds.     

Design,synthesis, and evaluation of the anticancer activity of 2‐amino‐aryl‐7‐aryl‐benzoxazole compounds

A series of 2‐amino‐aryl‐7‐aryl‐benzoxazole derivatives have been designed, synthesized, and evaluated as anticancer agents. Fourteen of the compounds exhibited cytotoxic effects toward human A549 lung cancer cells. We found 12l was the most potent with an EC₅₀ of 0.4 μm , equivalent to the anticancer drug doxorubicin, but had low selectivity following cross screening in monkey kidney Vero cells. Eight of the most potent or most selective compounds were further profiled in additional cell lines (MCF7, NCI‐H187, and KB) to better understand their cytotoxic activity. Only compound 12l had a measurable EC₅₀ in a single cell line (3.3 μm in the KB cell line). Taken together, this data suggest the series as a whole display specific cytotoxicity toward A549 cells. Cheminformatics searches pointed to JAK2 as a possible target. A subset of compounds assayed at this target showed IC₅₀s ranging from 10 to 0.08 μm ; however, no clear correlation between JAK2 potency and A549 cytotoxicity was observed.     

Synthesis,biological evaluation,and molecular docking studies of novel 3‐aryl‐5‐(alkyl‐thio)‐1H‐1,2,4‐triazoles derivatives targeting Mycobacterium tuberculosis

A small library of new 3‐aryl‐5‐(alkyl‐thio)‐1H‐1,2,4‐triazoles was synthesized and screened for the antimycobacterial potency against Mycobacterium tuberculosis H₃₇Ra strain and Mycobacterium bovis BCG both in active and dormant stage. Among the synthesized library, 25 compounds exhibited promising anti‐TB activity in the range of IC₅₀0.03–5.88 μg/ml for dormant stage and 20 compounds in the range of 0.03–6.96 μg/ml for active stage. Their lower toxicity (>100 μg/ml) and higher selectivity (SI = >10) against all cancer cell lines screened make them interesting compounds with potential antimycobacterial effects. Furthermore, to rationalize the observed biological activity data and to establish a structural basis for inhibition of M. tuberculosis, the molecular docking study was carried out against a potential target MTB CYP121 which revealed a significant correlation between the binding score and biological activity for these compounds. Cytotoxicity and in vivo pharmacokinetic studies suggested that 1,2,4‐triazole analogues have an acceptable safety index, in vivo stability and bio‐availability.     

Investigation of anti‐inflammatory,nitric oxide donating,vasorelaxation and ulcerogenic activities of 1, 3‐diphenylprop‐2‐en‐1‐one derivatives in animal models

The main aim of this work is to find out novel chemical moieties with potent anti‐inflammatory and vasorelaxant activities with reduced gastric toxicities. For fulfilling the above aim, here we investigated novel chalcones (1, 3‐diphenylprop‐2‐en‐1‐one derivatives) with nitric oxide (NO) and hydrogen sulphide (H₂S) donating potency for anti‐inflammatory activity by carrageenan‐induced rat paw oedema. These molecules then further evaluated for in‐vitro NO‐releasing potency and vasorelaxation effect on isolated adult goat aortic tissue. The promising molecules were further screened for ulcerogenic activity in the rat model. The tested compounds produced % inhibition in paw oedema ranging from 29.16% to 79.69% and standard drug Diclofenac sodium produced 85.30% reduction in paw oedema after 5 hours. Out of this dataset, compounds AI1, AI7, Ca1, B2, B10, D2, and E8 showed 73.01%, 79.69%, 75.02%, 75.46%, 74.35%, 73.9% and 74.35% reduction in paw oedema respectively, which is approximately 80%–90% to that of standard Diclofenac sodium. The compound Ca1 was found to release 0.870 ± 0.025 mol/mol of NO and standard Glyceryl trinitrate (GTN) was found to release 0.983 ± 0.063 mol/mol of NO. The compound Ca1 produced 950.2 μmol/L of EC₅₀ whereas standard GTN produced 975.8 μmol/L of EC₅₀ for aortic smooth relaxation. The compounds Ca1 produced 0.1117 of ulcer index which is far less than that of standard Diclofenac sodium (1.148). The potent lead molecules were further evaluated to understand the mechanism of vasorelaxation by using specific antagonists or blockers of NO and H₂S.     

4‐amino‐6‐alkyloxy‐2‐alkylthiopyrimidine derivatives as novel non‐nucleoside agonists for the adenosine A1 receptor

Three 4‐amino‐6‐alkyloxy‐2‐alkylthiopyrimidine derivatives ( 4 – 6 ) were investigated as potential non‐nucleoside agonists at human adenosine receptors (ARs). When tested in competition binding experiments, these compounds exhibited low micromolar affinity (K_i values comprised between 1.2 and 1.9 μm ) for the A₁ AR and no appreciable affinity for the A_2A and A₃ ARs. Evaluation of their efficacy profiles by measurement of intracellular cAMP levels revealed that 4 and 5 behave as non‐nucleoside agonists of the A₁ AR with EC₅₀ values of 0.47 and 0.87 μm , respectively. No clear concentration‐response curves could be instead obtained for 6 , probably because this compound modulates one or more additional targets, thus masking the putative effects exerted by its activation of A₁ AR. The three compounds were not able to modulate A_2B AR‐mediated cAMP accumulation induced by the non‐selective AR agonist NECA, thus demonstrating no affinity toward this receptor.     

Metronidazole containing pyrazole derivatives potently inhibit tyrosyl‐tRNA synthetase: design,synthesis, and biological evaluation

As an important enzyme in bacterial protein biosynthesis, tyrosyl‐tRNA synthetase (TyrRS) has been an absorbing therapeutic target for exploring novel antibacterial agents. A series of metronidazole‐based antibacterial agents has been synthesized and identified as TyrRS inhibitors with low cytotoxicity and significant antibacterial activity, especially against Gram‐negative organisms. Of the compounds obtained, 4f is the most potent agent which inhibited the growth of Pseudomonas aeruginosa ATCC 13525 (MIC = 0.98 μg/mL) and exhibited TryRS inhibitory activity (IC₅₀ = 0.92 μm ). Docking simulation was performed to further understand its potency. Membrane‐mediated apoptosis in P. aeruginosa was verified by flow cytometry.     

Synthesis,biological evaluation,and molecular docking studies of new pyrazol‐3‐one derivatives with aromatase inhibition activities

A new series derived from 4‐(2‐chloroacetyl)‐1,2‐dihydro‐1,5‐dimethyl‐2‐phenyl‐3H‐pyrazol‐3‐one was synthesized, characterized and its pharmacological activity toward aromatase enzyme inhibition was screened and compared to the reference native ligand letrozole. The most active compound of the series was 16 , showing IC₅₀ value of 0.0023 ± 0.0002 μm compared to letrozole with IC₅₀ of 0.0028 ± 0.0006 μm . In addition, compounds 26 and 36 exhibit good inhibition activities close to letrozole with IC₅₀ values 0.0033 ± 0.0001 and 0.0032 ± 0.0003 μm , respectively. Moreover, molecular docking studies were conducted to support the findings.     

3D‐quantitative structure‐activity relationship study for the design of novel enterovirus A71 3C protease inhibitors

A three‐dimensional quantitative structure‐activity relationships model of enterovirus A71 3C protease inhibitors was constructed in this study. The protein‐ligand interaction fingerprint was analyzed to generate a pharmacophore model. A predictive and reliable three‐dimensional quantitative structure‐activity relationships model was built based on the Flexible Alignment of AutoGPA. Moreover, three novel compounds ( I – III) were designed and evaluated for their biochemical activity against 3C protease and anti‐enterovirus A71 activity in vitro. III exhibited excellent inhibitory activity (IC₅₀ = 0.031 ± 0.005 μM, EC₅₀ = 0.036 ± 0.007 μM). Thus, this study provides a useful quantitative structure‐activity relationships model to develop potent inhibitors for enterovirus A71 3C protease.